Photosensitive glass



Patented July 18, 1950 OFFICEIZ PHOTOSENSITIVEGLASS StanleyrDo'nald:Stookey, CorningrN: Y1, flassignor to -GorningqGlasssworks, Corning, N.Y., a corporationofNew York Nwnmwifia mmonium-January's;194s,

Seria-lNo.1, 492}v I I i This inventionrelatesto theimanufa'cture' ofphotosensitive glasses andarticlstliereof, that is, glasses inwhichexposure'to short -wave'radiaf tions'suchas ultraviolet bringsabout aclfangeim the glass as a result of which irradiated areasarecapable of heat developed coloration; while non; irradiatediareasremain' substantially unchanged on heating;

Ina. the pending": applications: l Serial Number 5133541, filedby-William Hi Armistead:..and:Serial Numbers 513,443, 513,444 and513,445, filed by Stanley 1). Stockey, all of which were filed December8, 1943, and assigned to the assignee of this application, there aredescribed photosensitive glasses which contain as sensitizingconstituents small amounts of either gold or silver or copper. Theapplications also showithat the inclusion of a small amount of-ceriumdioxide in the glass, in addition to the sensitizing constituent,greatly improves the photosensitivity of theglass 10"'Claiins: (01.49-92) and the contrast and detail of' the images and I designs whichmay be formed'therein. According to the aforesaid disclosures,thephotbsensh.

tive glasses in which the-sensitizing constituentis either gold orsilver shouldpreferably bermeltedi ,25'I1eithel' increase nor diminishthe photosensitiVityl oxidizingly, but the glasseswhichcontaincopper:-

should be melted under reducingconditions. The glasses are at firstcolorless andtransparenteven after exposure toultravioletprlotherlshortwave] radiations, but when subsequently.reheated at temperatures below their softening points, the irradiatedareas become colored. If desired, the introduction of fluorine? intotheglasses.- causes them also to become opacified throughoutzwhenheated. Thus colored photographic images can be produced in the glass'either with a transparent lciacluground' or with an opal background. Itis further p'ointedout in applications 513,443 and 513,445that' thepresence in the glass of'ultraviolet absorbing: constituents and ofcertain oxides including. AS203 andr SbzOa, should; be: avoided becausethey inhibit "the'photosensitivity; oi the glass The necessary absence.of these oxidesincreaseswthe difficulty 'of fining the'glass; that is,eliminating bubbles therefrom..

One of thechief cbjects'oflthisinvention is'to; remove the bubblesfromphotosensitiveglasses during meltingwithout diminishing thephotosensitivity of the glass.

Another object is to increase the photosensitivity of theprior-glasses.-

I have now discovered that theintroduction of unrto-taboutxul of SbzOsinto the prior-glasses; containingsGeoz andeither gold, silver orcopper. increases:therphotosensitivity of the glasses and: aidshinning/them. Extremely small amounts Loft: SbzOyzimprove: thephctosensitivity of the'xglassa andzsincreasing amounts up to about 0.1%helpitot More than about 0.1% 310203 eliminate bubbles. causesa'decrease in photosensitivity, ,and ;1%i-.or more completely destroysit. On:the :contrary; AS203, although effective: in the eliminationazofzbubbles, destroys the photosensitivity even when present in quantitiesas small as a few hundredths of one pen cent.

The invention is generally eifective in silicate glasses and isparticularly effective in glasses which contain an oxide of a metal ofthe second periodic group up to and including barium or a plurality ofsuch oxides, it being known that the,

remaining elements of this group, mercuryrand but are-wasteful .ofthisexpensive-ingredient and hence are not recommended. The goldiswpreferablyutilized as the-chloride -bydissolving gold in acid and'addinglthesolution tolthe glass batch; ,As pointed out above; theflbatchpreferably should contain an oxidizing agent, such as an alkali metalnitrate.

Glasses in which the sensitizing "constituent-is silver preferablyshould contain silver equivalent to-about 0.05% to 0.3%: AgCL: Thesilver pref? erab'ly is incorporated in the batch asthe chloride butanycompound: of silver may be Y employed: An: oxidizing agent? also ispreferably included inthe batch.

Glasses-inf which therse-nsitizing constituent'xis copper preferablyshould (contain about 0.05% i to 1% of coppercomputedasGu'Q:Generallyfabout 0.5% produces :the bestresult, but in makingrglass'fibres for the production of photonsensitive glass f abrics; up to" '1of copper: computed :Ias JCnzOr'oi more; may be: required: The ibatch'eshould con tainra-reducing;agentsuch.as isuganori ammonium chlorideu.

In'ith'e foregoingrglasses theifinclusion: ofiupflto 0-;05L%1 of C902:improves the 2 ph'otcsensitivit'y of: the" glass by 'increasingiatheexposure speed; ten foldathat 'is, it decreases the time o fexposur'e"by 3 a factor of ten. Amounts greater than about 0.05% CeOzprevent penetration of the efiective radiations into the glass and henceinhibit photosensitivity.

A small limited amount of Sn02 may also be added to the glasses ifdesired, It improves the photosensitivity but is only about half aseffective as CeOz. In the gold or silver-containing glasses more thanabout 0.02% SnOz destroys photosensitivity by causing colorationthroughout the glass when heated. Copper-containing glasses may containlarger amounts, up to 0.5% Sn02 or more if desired, without ill effect.

Constituents which inhibit photosensitivity and position a suificientamount of fluorine. It is impossible to specify the exact amount offluorine which will be required in all cases because the amount willvary with the size of the batch, the time and temperature of melting,and the type of melting container employed; The proper amount for anygiven conditionsmay' easily be determined by trial.

The fluorine-containing glasses are transparent andcolorless whenfabricated into ware, but when reheated at 500 to 600 0., they becomeopaque or light-diffusing. Such a glass, when irradiated with short-waveradiations before reheating and while it is transparent, is affectedhence should be absent from the glass comprise R5 50 that when it isthereafter reheated, it not only oxides of arsenic, iron, manganese,vanadium,.

becomes opaque or light-diffusing, but the irradiated parts of the glassbecome permanently coloredj If selectively irradiated, that is, if partsofthe glassare shielded from the effective radiat'ion's, the shieldedparts will be opacified but not colored on being reheated. By this meansornamental designs and images can be reproduced in the glass byconventional photographic printing methods and such images and designsis a combination of the colors produced by each alone. W111 appear witha high degree of sharpness and As examples of glass compositionsillustrating detail against the opacified background; butv notlimitingthe invention, the following As examples of compositions for opacifiablebatches in parts by weight are given: glasses illustrating but notlimiting the inven- Table I s s s 7 1 4 4 '4 10.5 10.5 10 10 10 17 Eachof the above batches contains SbzOs which fines the glass during meltingand increases its photosensitivity. Although the presence of 310203 issufiicient for fining the glass, I have found that up to" about 1%, of asulfate such as CaSO4 or 60 salt cake, introduced into the batch, on theoxide basis in addition to the SbzOs as shown in Exainples 3 and 5,seems to further improve the fining rate of the glass and to increaseits photosensitivity very slightly but appreciably. Compositions 3, 4and 5 are particularly suitable for the production of rolled sheetglass.

The glasses resulting from melting the batches of vTable I aretransparent but in come cases it may be desirable that they be opacifiedthroughout in order to provide a, white background for the image ordesign to be formed in the glass by selective irradiation followed byheat treatment. The glasses may be rendered thermally and controllablyopacifiable by including intheir .com-

tlon, the following batches, in parts by weight, are given:

Table II .In ltheiabove compositionsreach batch scone tains a fluorideas-zan opacifying agent'za come, pound of -gold,. silver ='or ".copperas :a'zsensitizing agent, -2Ce0gz .forsincreasing the photosensitivityand SbzOx for increasing the photosensitivity and 'eliininating bubbles:during:melting. .yBatches containingcopper contain {also a rreducing.agent which :may be :a carbonaceous .:material :or ammonium chloride.'Th'eachl'oride ;seems also .to assist in thezopacificationof theglass-and for this reason, although it is not essential, :sodiumchloride :is added -to #1311056 :batches which contain noammoniumchloride. The;batches"which contain gold or silver areireefromireducingwagents.

The amounts of opacifyingmnd ireducing agents will vary with the sizeand conditions of melting. The above batches, when melted for about 4hours at about 1350i in crucibles of -.onepound capacity, producetransparent, .rcolorless photosensitive glasses which are free frombubbles and 'which become opacified "throughout when reheated at 500 to600 C.

The time or durationnfiexposure to shortwave radiations whicnisnecessaryin orde'r to obtain an effect in the glasses of Tables I and II whichcan be developed into a coloration by heating will vary, depending uponthe intensity of the effective radiations, that is, the source of theradiations and its distance from the glass during exposure. The time andintensity necessary for a desired efiect can easily be determined bytrial. For example, a five-minute direct exposure at a distance of eightinches from a 60- ampere carbon arc will produce a blue coloration in aglass containing gold, C602 and an oxidizing agent when subsequentlyheated for about minutes at 550 C. Somewhat longer exposures arerequired for the copper and silvercontaining glasses.

Although ultraviolet emitting lamps, such as the carbon are or thequartz mercury arc, are convenient sources of short-wave radiationseffective for my purpose, it'is my intention to include X-rays,radioactive radiations, etc., within the scope of the invention.

The temperature or time of heat treatment of the glasses necessary forthe development of coloration in the irradiated parts will depend uponhow greatly the photosensitizin constituent in the glass has beenaffected by the irradiation. The most suitable temperatures are between500 and 600 C. Long treatments at the lower temperatures are aseffective as short treatments at the higher temperatures. Thirty minutesat 550 C. is a suitable average heat treatment.

The color which is produced in the glasses depends upon thephotosensitizing constituent which is present, and in the case of goldit depends also upon the time and intensity of the exposure and theduration and temperature of heating. Copper-containing glasses developvarious shades of red. The color'of the gold-containing glasses may varyfrom blue through lavender, purple, and maroon to red, changing in thatorder as the efiective exposure is increased or as the time andtemperature of heating are raised. The silver-containing glasses developeither a bright yellow or an amber color. In general, thesilver-containing glasses resemble the old-containing glasses in theirreactions, and both silver and gold may be present in the same glasswhereupon the resulting colors will be various shades of red and amber.Like the gold glass, the photosensitive efiects of the silver glass areinhibited by the presenceiof:substantialzcope per. 1

As a result of the improved,photosensitivityiof the glasses :accordingto thednventio .-.due.-ito the ;presence therein of both GeQzsand.r'SbZQL photographicjlnegatives can be employed in the conventionalmanner using an ultraviolet light source or :even direct vsunlight 'to:make heate developed :images in the glass, the images being equal in'detail-=.and contrast to .lchemically 71'6- duced images printed1in:like lmanner upon photoraphic;pri ngzpap i h The .term -,-.-silicate,g1ass:a'siused in the; claims means :a {glass prepared =byfusion-ofzraw glass-r making :materials containing .on the oxide .basisa major proportion :.of-si1ica.-and a minor -.pr,o portion of an alkalimetal oxide ssuch rassodium oxide -or potassium oxide, :preferablycontaining a minor @roportion of anoxideof .a metalaofzthe secondperiodic vgroup up toand including shar iumior 5a pluralityrofrsuchoxidesc Optionallymontaining ea minor proportion :of anotherconventionalglass forming -oxide such as :A12O31Qil'd PbQ, and, ifdesired, containing .:-.sufiicient .fiuorine to make the (glassthermally I opacifiable, :but being free of constituents which inhibitphotosensitivity including compounds of arsenic, iron, manganese,vanadium, selenium, thallium, and uranium and also over 2% PbO.

I claim:

1. A photosensitive glass consisting essentially of a silicate glasscontaining on the oxide basis by weight the indicated proportion of aphotosensitizing constituent selected from the group consisting of 0.01%to 0.1% gold computed as Au, 0.05% to 0.3% silver computed as AgCl, and0.05% to 1% copper computed as CuzO, up to 0.05% (3e02, and up to 0.1%SbzOs.

2. A photosensitive glass consisting essentially of a silicate glasscontaining, on the oxide basis by weight as calculated from the batch,the indicated proportion of a photosensitizing constituent selected fromthe group consisting of 0.01% to 0.1% gold computed as Au, 0.05% to 0.3%silver computed as AgCl, and 0.05% to 1% copper computed as CuzO, up to0.05% 0e02, and up to 0.1% Sb203, and also containing SO: in an amountup to 1%.

3. A photosensitive glass consisting essentially of a thermallyopacifiable, fluorine-containing silicate glass containing on the oxidebasis by weight the indicated proportion of a photosensitizingconstituent selected from the group consisting of 0.01% to 0.1% goldcomputed as Au, 0.05% to 0.3% silver computed as AgCl, and 0.05% to 1%copper computed as CuzO, up to 0.05% CeOz, and up to 0.1% SbzOa.

4. A photosensitive glass consisting essentially of an oxidized silicateglass containing on the oxide basis by weight 0.01% to 0.1% goldcomputed as Au, up to 0.05% C602, and up to 0.1% of antimony oxidecomputed as SbzOs.

5. A photosensitive glass consisting essentially of an oxidized silicateglass containing on the oxide basis by weight 0.05% to 0.3% of silvercomputed as AgCl, up to 0.05% 0e02, and up to 0.1% of antimony oxidecomputed as SbzOs.

6. A photosensitive glass consisting essentially of a reduced silicateglass containing on the oxide basis by Weight 0.05% to 1% coppercomputed as CuzO, up to 0.05% cerium oxide computed as CeOz, and up to0.1% SbzOa.

7. A photosensitive glass consisting essentially of a reduced silicateglass containing on the oxide basis by weight 0.05% to 1% coppercomputed as 01120, up to 0. 05%. cerium oxide computed as e02, up to0.1% SbzOa, and up to 0.5% tin oxide computedasSnOa" An articlecomprising a body-0f irradiated photosensitive glass consisting,essentially of a silicate 'glasscontaining on the oxide basis by weightthe indicated proportion of aphotosensitizing constituent selected fromthe group consisting of 0.01% to 0.1%gold computed'as Au,- 0.05%- to0.3% silver computed asYAgCI; and 0.05% to 1% copper computed as Cu2O,up to 0.05% C602, and up to 0.1% Sb2O3, said glass body containingwithin its mass a predetermined latent photographic image capable ofbeingdeveloped, by uniform'heating of theentire glass body, into avisible, colored image exhibiting photographic detail. l I 9;;Anarticlecomprising a glass body made of a photosensitive glassconsistingessentially of a silicate glass containing'on the oxide basis by weightthe indicated proportion of a photosensi tizing constituent selectedfrom the groupconsisting-of 0.01% to 0.1% gold computed as-Au, 0.05% to0.3% silver computedas AgCl, and

0.05% to 1% copper computed as CuzO, up to 8 0.05%-cam, andup to 0.1%SbzOa, Selected portions of said glassbody being colored by thephotosensitizing constituent to form within its mass a heat-stable imageexhibiting photographic detail.

10'. An article comprising a glass body made of a photosensitive glassconsisting essentially of an oxidized, silicate glass containing on theoxide basis by weight 0.01% to 0.1% gold computed as Au, up to 0.05%CeOzand up to 0.1% of antimony oxide computed as SbzOs, selectedportions of said glass bodybeing colored by the gold to form within itsmass a heat-stable image exhibiting photographic detail.

. 'STANLEY DONALD STOOKEY.

REFERENCES CITED The following references are of record in the file ofthis patent? UNITED STATES PATENTS Number Name Date 2,049,765 FischerAug. 4, 1936 2,422,472 Dalton June 1'7, 194:7

7. A PHOTOSENSITIVE GLASS CONSISTING ESSENTIALLY OF A REDUCED SILICATEGLASS CONTAINING ON THE OXIDE BASIS BY WEIGHT 0.05% TO 1% COPPERCOMPUTER AS CU2O, UP TO 0.05% CERIUM OXIDE COMPUTED AS CEO2, UP TO 0.1%SB2O3, AND UP TO 0.5% TIN OXIDE COMPUTED AS SNO2.